Halogen cycle incandescent lamp



May 20,1969 J. GjcmnwELL. Jnv 3,445,713 HALOGEN CYCLE IN'cANnEscEN'r-LAMP v Filed Dec. 12. l196e United States Patent O U.S. Cl. 313-273 6Claims ABSTRACT OF THE DISCLOSURE An incandescent halogen cycle lampembodying a planar type filament and unique supporting structure,wherein the lamp envelope has a pinch seal at least at one (lower) endand which is located in a plane which generally contains the coiledsegments of a planar filament. The outermost segments at each side ofthe filament serve as legs which snugly receive lead-in conductors whichextend into and through the pinch seal. Inner segments of the filamentare additionally supported at their lower ends by one or more supportsextending from the pinch seal and engaging bight portions betweenadjacent segments. Depending upon the number of inner segments, they maybe supported at their upper ends by one or more auxiliary support wireswhich may be anchored in an elongated bead or bridge extending betweenportions of the lead-in conductors which extend beyond the upper end ofthe filament. Such auxiliary support wires may also be anchored in asecond pinch seal at the end of the envelope opposite thefirst-mentioned pinch seal.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates generally to electric incandescent lamps comprising a sealedenvelope containing an incandescible filament. More particularly, theinvention relates to lamps of the halogen cycle type comprising atungsten filament and a gaseous atmosphere comprising a halogen whichfunctions as a regenerative getter by reacting with tungsten particlesvaporized from the filament to form a tungsten-halogen compound whichreturns to the vicinity of the filament Where it is dissociated and thetungsten is deposited back upon the filament.

Description of the prior art It is a requirement of halogen cycle lampsthat the envelope be of compact size and shape such that the entireinterior surface of the envelope be at a minimum wall temperaturesuiiicient to effect the reaction between the tungsten and the halogen,and that the envelope interior be devoid of substantial pockets whereinhalogen com pound might condense with eventual removal of halogen fromeffective relationship with the filament and the hot bulb walls.

In most cases the filament has heretofore been in the form of a simplehelical coil or coiled-coil extending axially of a cylindrical bulb orenvelope as for example, in Patent 2,883,571--Fridrich et al., assignedto the same assignee as the present invention.

For certain high intensity lighting applications, such as movie lightunits, there has been a need for an improved lamp having a planar typelament, that is, one which comprises a plurality of coiled segmentsarranged in generally parallel side-by-side relationship, in or closelyadjacent to a single plane and having the desirable features of thehalogen cycle incandescent lamp, namely, longer life, greater totallight output over life, higher stability of output and color and acompact size.

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Accordingly, it is an object of this invention to provide a halogencycle lamp in a compact envelope only slightly arger than the planartype filament and having the abovestated features which are inherent inhalogen cycle lamps.

It is also an object to provide such a lamp having a support structureof comparatively simple form with a minimum of internal components forcomparatively simple assembly and to eliminate the possibility ofadversely affecting the halogen regenerative cycle.

SUMMARY In accordance with one aspect of the invention, the aboveobjectives are achieved by providing a lamp construction wherein theenvelope is provided with a flattened pinch seal at least at the lowerlongitudinal end thereof, and the planar filament is arranged to besubstantially in a common plane which also includes the said pinch seal,with a pair of lead-in conductors extending through the said pinch sealinto the envelope and through respective outermost side segments of thefilament and fitted closely Within said segments to provide a sturdysupport, and with at least one lower support wire having one end thereofengaging a bight portion connecting the lower ends of adjacent segmentsof the filament and its other end embedded and anchored in said pinchseal.

In accordance with a further aspect of the invention, the said lead-inconductors may be extended beyond the ends of the said outermostfilament segments to a point above the filament, an elongated bead,preferably of fused silica, extends transversely of the envelope abovethe filament and between the upper ends of said lead-in conductors withportions of said conductors anchored in said bead, and with at least oneupper support wire having one end thereof engaging a bight portionconnecting the upper ends of adjacent segments of the filament and itsother end anchored in said bead.

In accordance with a still further aspect of the invention, a secondpinch seal may be provided at the upper end of the envelope, and atleast one upper support Wire has one end thereof engaging a bightportion at the upper end of the filament and its other end embedded andanchored in said second pinch seal.

BRIEF DESCRIPTION OF THE DRAWING Further features and advantages of theinvention will appear from the following detailed description of speciesthereof and from the drawing wherein:

FIG. 1 is a front elevation of a lamp comprising the invention;

FIG. 2 is a front elevation of another species of the invention;

FIG. 3 is a side elevation of the FIG. 2 lamp turned at an angle ofninety degrees from the FIG. 2 view; and

FIG. 4 is a front elevation of still another species of lamp comprisingthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of thedrawing, the incandescent halogen cycle lamp illustrated thereincomprises an envelope 1 which is preferably composed of essentiallyfused silica such as quartz, or the material known as Vycor or as 96%silica glass, and having a flattened compressed portion or pinch seal 2at its lower end (as shown in FIG. l) which hermetically seals theenvelope from the atmosphere. The envelope 1 contains a filling of inertgas such as argon, plus a small amount of a halogen such as iodine orbromine or compounds thereof which function as a regenerative getter.The evacuation and gas filling is performed through the upper end (asshown in FIG. 1) of the length of tubing of which the envelope 1 isconstituted and tipped off at 3.

Filament 4, preferably of tungsten wire, in this case comprises a pairof helically coiled-coil inner segments 5 which constitute the lightsource proper, and a pair of outer or side segments 11 which serve asleg portions as hereinafter explained, all said segments being arrangedin a generally parallel side-by-side relation in or adjacent to a commonplane. The common plane defined by the segments S and 11 closelycoincides with the plane containing the pinch seal 2 at the lower end ofthe envelope. The coiled-coil segments 5 are electrically connected inseries by a lower bight portion 6 of filament 4, preferably a loop ofcoiled tungsten wire, between the adjacent segments 5. A lower supportwire 7 is attached at one end by a hook portion to the lower bightportion `6 and the other end is embedded in pinch seal 2. Lower supportwire 7 insures alignment of the coiled-coil segments 5 during lampoperation when the heating and cooling which expands and contracts thesegments tends to distort them; in addition, it holds the filament inposition in case of vibration or shock such as during shipping orinstallation of the lamp.

Lead-in conductors 8 comprise inner portions 9 of rigid tungsten ormolybdenum wire, which have one (lower) end 10 (as viewed in FIG. l),embedded in the pinch seal 2 and extend in parallel relationshiplongitudinally into the envelope. Inner portions 9 preferably areclosely fitted along their entire length within the interior of thecoiled outermost segments or leg portions 11 of filament 4. The legportions 11 are preferably securely affixed to the inner portion 9 ofthe lead-in conductor 8 by tack welding, preferably at the lower end 10which is embedded in the pinch seal '2.

Inner portions 9 of lead-in conductors 8 are electrically connected,preferably by tack welding, to outer portions 12, preferably composed ofmolybdenum or tungsten, at a flattened or foliated portion 13` which ishermetically sealed in pinch 2.

The diameter of the envelope 1 is correlated with the size of thefilament 4 to maintain a short distance between the lament and theenvelope wall to insure proper performance of the halogen regenerativecycle.

Referring to the species shown in FIG. 2, the filament 4a, preferably oftungsten wire, comprises a plurality of helically coiled inner segments5a and outer segments 8a which are in a generally parallel side-by-siderelation in or adjacent to a common plane. As in the previousernbodiment, the common plane defined by the coil segments 5a, 8aclosely coincides with the plane containing pinch seal 2 at the lowerend of the envelope 1 (see FIG. 3). The coil segments 5a (four, or anyother even number) are electrically connected in series by upper andlower intermediate loop or bight portions 14 and 6a, respectively. Theoutermost segments or legs 8a are similarly connected to the adjacentsegments 5a at their upper ends.

Inner portions 9a of lead-in conductors 8 are closely fitted along theirlength within the full length of the interior of the helically coiledoutermost segment or leg portions 8a of filament 4a, and theyadditionally extend beyond the top of filament 4a as shown at 15. To addrigidity and to insure proper alignment of the filament the ends ofupper portions 15 of the inner portions 9a of lead-in conductors 8 areembedded in an elongated bead or bridge 16, preferably of quartz or highsilica content glass.

The lower ends of inner lead portions 9a are electrically connected,preferably by tack welding, to outer portions 12a at attened or foliatedportions 13a which are hermetically sealed in pinch 2.

To provide further support and alignment for the upper portion of the'filament 4a, an upper support wire 17 is attached at one hook-shapedend to intermediate bight portion 14 and the other end is embedded inbead 16. The lower portion of filament 4a is held in position by lowersupport wires 7a which are each attached at one hook-shaped end to alower bight portion 6a and have their other ends embedded in pinch seal2.

When desired, the lamp shown in FIG. 2 may contain a refiector 18located behind the filament 4a and in close proximity thereto (as alsoshown in FIG. 3). As illustrated therein, the refiector 18 is preferablycomposed of sheet molybdenum, and is supported by a pair of supportwires 19 which have their ends embedded in the bridge or bead 16 (seeFIG. 3). The exact geometric shape and location of reflector 18 is notcritical in the optical system of a light projection device; it ispreferably of approximately the shape of the filament structure and istherefore of a substantially rectangular shape and is also preferablydish-shaped within its boundaries. Such a reflector acts to direct lightin a direction to increase the apparent brightness of the light source.The spaces between the turns and segments of the filament coils are atleast partially lled in with light, the effect of which is to increasethe black body characteristics of the surface and to thereby increasethe apparent brightness of the source.

In FIG. 4, still another spieces of the invention is illustrated whichhas pinch seals at both ends of the envelope. The second pinch seal 2ais formed at the upper longitudinal end of envelope 1 and in a planecoincident with the lower pinch seal 2 and filament segments 5a. Theinner portions 9 of lead-in conductor 8 extend longitudinally of theenvelope only to the upper portion (as viewed in FIG. 4) of filament 4a.The leg segments 8a of filament 4a are closely fitted along the entirelength of the inner lead portions 9.

Additional support and alignment is provided for the upper portion ofthe filament 4a by upper support wire 17a which is attached at onehook-shaped end to intermediate bight portion 14a and the other endembedded in the second pinch seal 2a. If further support is desired ornecessary, additional upper support 17b may be attached to the bightportions connecting the leg segments 8a and the adjacent segments 5a asshown in broken lines in FIG. 4.

The pinch seals 2 (and 2a) may be of a conventional confined type whichis of I-shaped cross-section having side rail portions 21, and which mayalso have a central longitudinal rib 22 along each of its fiat surfaces.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric incandescent halogen cycle lamp comprising a compactenvelope of essentially fused silica having an external flattened pinchseal at the longitudinal lower end thereof and containing an inert gasfilling and a halogen functioning as a regenerative getter, a planartype filament comprising a plurality of coiled tungsten wire segmentsarranged in side-by-side relation longitudinally of the envelope andclosely adjacent a common plane which also includes said pinch seal, theproximate ends of adjacent said segments being serially connected bybight portions, a pair of lead-in conductors extending through saidpinch seal with rigid inner portions thereof anchored in said pinch sealand extending into the envelope and through respective outermost saidsegments of the filament to the upper end of the filament and fittedclosely within said segments, and at least one lower support wire havingone end thereof engaging a bight portion at the lower end of thefilament and its other end embedded and anchored directly in said pinchseal.

2. A lamp as set forth in claim 1 wherein the said outermost segmentsextend downwardly along said rigid inner portions of the lead-inconductors to a point within the said pinch seal.

3. A lamp as set forth in claim 1 wherein the said rigid inner portionsof the lead-in conductors extend beyond the ends of said outer-mostfilament segments to a point above the filament, an elongated bead ofvitreous material extending transversely of the envelope above thefilament and between the upper ends of said lead-in conductors withportions of said conductors anchored in said bead, at least one uppersupport Wire having one end thereof engaging a bight portion at theupper end of the filament and its other end anchored in said bead.

4. A lamp as set forth in claim 3 including a proximity reflector memberbehind said filament, and means supporting said reflector from saidbead.

5. A lamp as set forth in claim 1 wherein the envelope has a secondflattened pinch seal at its longitudinal upper end and also located insaid common plane, at least one upper support wire having one endthereof engaging a bight portion at the upper end of the filament andits other end embedded and anchored in said second pinch seal.

6. An electric incandescent halogen cycle lamp comprising a compactenvelope of essentially fused silica having an external flattened pinchseal at the lower longitudinal end thereof and containing an inert gasfilling and a halogen functioning as a regenerative getter, a filamentcomprising a pair of helically coiled-coil segments arranged inside-by-side relation longitudinally of the envelope and closelyadjacent a common plane which also includes said pinch seal, the lowerends of said segment being serially connected by a bight portion, a pairof leadin conductors extending through said pinch seal with rigid innerportions Ithereof anchored in said pinch seal and extending into theenvelope alongside respective said filament segments and up t0 the upperends thereof, the upper ends of said segments terminating in helicallysingle coiled segments which are fitted snugly around respective saidrigid inner portions of the lead-in conductors, and a lower support wirehaving one end thereof engaging the bight portion at the lower ends ofsaid coiled-coil segments and its other end embedded and anchoreddirectly in said pinch seal. j

References Cited UNITED STATES PATENTS 1,925,857 9/1933 Van Liempt313-218 2,605,440 7/1952 Gero 313-273 X 3,082,345 3/1963 Bottone 313-115X 3,211,942 10/1965 Wiley 313-315 3,355,619 11/1967 Reed 313-273 X JAMESW. LAWRENCE, Primary Examiner.

R. F. HOSSFELD, Assistant Examiner.

US. CI. X.R.

